The invention relates to the field of digital subscriber line (DSL) technology, and more particularly, to techniques for performing loop diagnostics on DSL systems.
Generally, there is a need for delivery of broadband services to consumers. One of the more prominent broadband solutions is DSL technology. A popular type of DSL is asymmetric digital subscriber line (ADSL), although other types of DSL are also available (e.g., very high-bit-ratexe2x80x94VDSL, symmetric high-bit-ratexe2x80x94SHDSL, and high-bit-ratexe2x80x94HDSL). Typically, such DSL services are delivered to consumers by the existing copper wire infrastructure. As such, vendors seeking to provide DSL solutions must contend with widely varying line conditions. Loop diagnostic information allows vendors to characterize given line conditions thereby facilitating deployment of DSL services. Loop diagnostic information might include information such as loop attenuation and quiet noise PSD (power spectral density), and other relevant information (e.g., signal to noise ratio).
Availability of such diagnostic information is useful, for example, on links where initialization fails (for whatever reason, such as a defective modem). Likewise, diagnostic information can be useful when link initialization does not fail (such as in the provisioning of new services). The loop diagnostic information may be exchanged during data mode (e.g., SHOWTIME) through messages over a message-based overhead channel when link initialization succeeds. However, when modems are not able to pass user data due to a failed initialization, the data mode approach cannot be used. In addition, the integrity and reliability of the loop diagnostic information obtained and or derived during failed link activation attempts is questionable. Thus, another diagnostic information exchange mechanism is required for such cases.
There is a need, therefore, for a reliable and robust mechanism for collecting and exchanging loop diagnostic information in the event of link activation failure. In a more general sense, there is a need for loop diagnostic techniques that can be used in troubleshooting a communication link.
The present invention provides techniques for performing loop diagnostics in DSL communication systems. One embodiment includes receiving a probe signal having known transmit characteristics, and determining loop diagnostic information based on the known transmit characteristics and received signal characteristics. Such loop diagnostic information can be useful in a preactivation mode, for example, in troubleshooting link activation failures or otherwise troublesome communication links. Likewise, such diagnostic information can be useful in general troubleshooting mode (regardless of link activation status) in gathering loop characteristics that support configuration and management of the DSL service in an offline loop diagnostic mode.
The features and advantages described in the specification are not all-inclusive and, in particular, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specification, and claims. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and not to limit the scope of the inventive subject matter